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Embedded Programming with Modern C++

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Explore how to use std::unique_ptr to safely manage object lifecycles and memory in Modern C++. Understand ownership transfer with move semantics, specialized array handling, and how smart pointers automate resource cleanup. This lesson also introduces shared pointers for advanced memory management.

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Example 1

C++
// uniquePtr.cpp
#include <iostream>
#include <memory>
#include <utility>
struct MyInt{
  MyInt(int i):i_(i){}
  ~MyInt(){
    std::cout << "Good bye from " << i_ << std::endl;
  }
  int i_;
};
int main(){
  std::cout << std::endl;
  std::unique_ptr<MyInt> uniquePtr1{ new MyInt(1998) };
  std::cout << "uniquePtr1.get(): " << uniquePtr1.get() << std::endl;
  std::unique_ptr<MyInt> uniquePtr2;
  uniquePtr2= std::move(uniquePtr1);
  std::cout << "uniquePtr1.get(): " << uniquePtr1.get() << std::endl;
  std::cout << "uniquePtr2.get(): " << uniquePtr2.get() << std::endl;
  std::cout << std::endl;
  {
    std::unique_ptr<MyInt> localPtr{ new MyInt(2003) };
  }
  std::cout << std::endl;
  uniquePtr2.reset(new MyInt(2011));
  MyInt* myInt= uniquePtr2.release();
  delete myInt;
  std::cout << std::endl;
  std::unique_ptr<MyInt> uniquePtr3{ new MyInt(2017) };
  std::unique_ptr<MyInt> uniquePtr4{ new MyInt(2022) };
  std::cout << "uniquePtr3.get(): " << uniquePtr3.get() << std::endl;
  std::cout << "uniquePtr4.get(): " << uniquePtr4.get() << std::endl;
  std::swap(uniquePtr3, uniquePtr4);
  std::cout << "uniquePtr3.get(): " << uniquePtr3.get() << std::endl;
  std::cout << "uniquePtr4.get(): " << uniquePtr4.get() << std::endl;
  std::cout << std::endl;
}

Explanation

  • The class MyInt (line 7 -17) is a simple wrapper for a number. We have adjusted the destructor in line 11 - 13 for observing the life cycle of MyInt.

  • We create, in line 24, a std::unique_ptr and return, in line 26, the address of its resource new MyInt(1998). Afterward, we move the uniquePtr1 to ...